"""
Reed-Solomon FEC implementation (baseline version).

This is the baseline FEC implementation for comparison.
"""

from typing import List, Optional, Dict, Any, TYPE_CHECKING
from ..logger_config import log_info, log_debug, log_warning, log_error, log_success, log_failure, log_progress, log_connection, log_media, log_stats
import time
import random

try:
    from .base import BaseFecCodec, FecConfig, FecPacket
except ImportError:
    from base import BaseFecCodec, FecConfig, FecPacket
# 延迟导入以避免循环依赖
if TYPE_CHECKING:
    try:
        from ..rtp import RtpPacket
    except ImportError:
        from rtp import RtpPacket


class ReedSolomonFec(BaseFecCodec):
    """Reed-Solomon FEC实现（基线版本）"""
    
    def __init__(self, config: FecConfig):
        super().__init__(config)
        # 简化的RS实现，用于基线测试
        self.field_size = 256
        self.generator_polynomial = self._generate_polynomial()
    
    def encode(self, packets: List['RtpPacket']) -> List[FecPacket]:
        """RS编码（简化实现）"""
        if len(packets) != self.config.k:
            raise ValueError(f"Expected {self.config.k} packets, got {len(packets)}")
        
        # 提取RTP包负载
        payloads = [pkt.payload for pkt in packets]
        
        # 简化的RS编码（实际项目中应该使用真正的RS库）
        repair_payloads = self._simple_rs_encode(payloads)
        
        # 生成FEC包
        fec_packets = []
        for i, repair_payload in enumerate(repair_payloads):
            fec_packet = FecPacket(
                fec_payload_id=self.sequence_number + i,
                repair_payload=repair_payload,
                protected_sequence_numbers=[pkt.sequence_number for pkt in packets],
                fec_type='reed_solomon'
            )
            fec_packets.append(fec_packet)
        
        self.sequence_number += len(fec_packets)
        self.stats['encoded_packets'] += len(fec_packets)
        
        return fec_packets
    
    def decode(self, original_packets: List[Optional['RtpPacket']], 
               fec_packets: List[FecPacket]) -> List[Optional['RtpPacket']]:
        """RS解码（简化实现）"""
        self.stats['decoded_packets'] += 1
        
        if not fec_packets:
            return original_packets
        
        # 简化的RS解码
        try:
            repaired_payloads = self._simple_rs_decode(original_packets, fec_packets)
            
            # 创建修复的包
            result = []
            for i, payload in enumerate(repaired_payloads):
                if payload is not None:
                    # 创建修复的RTP包
                    # 在运行时导入RtpPacket，避免循环导入
                    try:
                        from ..rtp import RtpPacket as RuntimeRtpPacket
                    except ImportError:
                        from rtp import RtpPacket as RuntimeRtpPacket
                    repaired_packet = RuntimeRtpPacket(
                        payload_type=96,
                        sequence_number=i,
                        timestamp=int(time.time() * 90000),
                        payload=payload
                    )
                    result.append(repaired_packet)
                    self.stats['recovered_packets'] += 1
                else:
                    result.append(None)
                    if original_packets[i] is None:
                        self.stats['failed_recoveries'] += 1
            
            return result
        except Exception:
            # 解码失败
            self.stats['failed_recoveries'] += sum(1 for p in original_packets if p is None)
            return original_packets
    
    def can_repair(self, lost_packets: List[int], 
                   available_fec_packets: List[FecPacket]) -> bool:
        """检查是否可以用可用FEC包修复丢失的包"""
        if not available_fec_packets:
            return False
        
        # RS可以修复最多 (n-k) 个丢失的包
        max_repairable = self.config.n - self.config.k
        return len(lost_packets) <= max_repairable
    
    def _generate_polynomial(self) -> List[int]:
        """生成生成多项式（简化）"""
        # 简化的生成多项式
        return [1, 2, 4, 8, 16, 32, 64, 128]
    
    def _simple_rs_encode(self, payloads: List[bytes]) -> List[bytes]:
        """简化的RS编码"""
        # 这是一个简化的实现，实际应该使用真正的RS库
        repair_payloads = []
        redundancy_count = self.config.n - self.config.k
        
        for i in range(redundancy_count):
            # 简单的XOR编码作为RS的替代
            repair_payload = b'\x00' * max(len(p) for p in payloads)
            for j, payload in enumerate(payloads):
                if j < len(repair_payload):
                    repair_payload = bytes(a ^ b for a, b in zip(repair_payload, payload.ljust(len(repair_payload), b'\x00')))
            repair_payloads.append(repair_payload)
        
        return repair_payloads
    
    def _simple_rs_decode(self, original_packets: List[Optional["RtpPacket"]], 
                         fec_packets: List[FecPacket]) -> List[Optional[bytes]]:
        """简化的RS解码"""
        # 提取可用的原始包负载
        available_payloads = []
        missing_indices = []
        
        for i, packet in enumerate(original_packets):
            if packet is not None:
                available_payloads.append(packet.payload)
            else:
                available_payloads.append(None)
                missing_indices.append(i)
        
        # 简化的解码逻辑
        if len(missing_indices) == 0:
            return available_payloads
        
        if len(missing_indices) > len(fec_packets):
            # 丢失的包太多，无法修复
            return available_payloads
        
        # 尝试修复（简化实现）
        for i, missing_idx in enumerate(missing_indices):
            if i < len(fec_packets):
                # 使用FEC包修复
                fec_payload = fec_packets[i].repair_payload
                available_payloads[missing_idx] = fec_payload
        
        return available_payloads